brevity is shortness of duration, and especially shortness or conciseness of expression — the quality of saying something in fewer words than it might have taken.
Both senses are live. The first is temporal and applies to anything that does not last: the brevity of a visit, of a season, of a life. The second is rhetorical and dominates ordinary use, describing speech or prose that has been compressed rather than merely cut off. The difference matters, because the rhetorical sense carries an implication the temporal one does not — that something was removed deliberately. A short statement is not automatically brief in this sense; brevity implies a longer version existed and was refused.
The word entered English around 1500 from the Latin brevitatem (nominative brevitas), "shortness" in space or in time, from brevis, "short" — the same root behind brief, abbreviate, and abridge. The Latin was already double in meaning, covering physical extent and duration alike, and English inherited both.
Brevity measures length, not force. A remark can be brief and still land on nothing, which is what separates it from 📝cogent expression, where the test is whether the point compels. Its working opposite is 📝circumlocution, the habit of circling an idea in more words than it requires. The observation that recurs among writers who prize brevity is that it is expensive: compression moves labour off the reader and onto the author.
📝"I have made this longer than usual because I have not had time to make it shorter." ~ 📝Blaise Pascal
"It is my ambition to say in ten sentences what others say in a whole book." ~ 📝Friedrich Nietzsche
"The secret of being boring is to say everything." ~ Voltaire